takeWhile method Null safety
override
Eagerly selects a leading sequence of characters.
Checks each character, from first to last, against test,
until one is found where test returns false.
The characters up to, but not including, the first one
where test returns false are included in the result.
If no characters test false, the entire sequence of character
is returned.
Implementation
@override
Characters takeWhile(bool Function(String) test);